A. What are your hobbies?(my hobby is playing games) ---> My hobby is playing games.  (Capitalization) (Punctuation)

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I'm staying there for six days this Saturday. --> This Saturday. I'll be there for six days. 

​You're gonna write me a letter, right? --> Can you write me a letter?

Of course, I'll write you an email.  --> Sure. I'll send you an e-mail. 

=> Another way: Your sentence is okay and this is another way of saying it.

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